JP2011251526A - Soft lithography device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and a method capable of easily and efficiently controlling the application pressure of a stamp or a macro-stamp for soft lithography on a surface of a substrate, and progressing automation.SOLUTION: The device for soft lithography by transfer includes a flexible stamp capable of achieving a deposit of a micro-structure or a nano-structure on a substrate. In the device, the flexible stamp 1 is constituted of: a layer 3 formed of an elastomer and including a structure surface 31 capable of achieving the deposit by transfer on its one surface; and a second layer 2 which is formed of an elastomer in a state of being closely connected to a surface of the first layer 3 facing the structure surface, and formed of an elastomer with particles each formed of a soft ferromagnetic material dispersed therein.

Description

  The present invention relates to a soft stamping lithography apparatus and method for structurally depositing molecules on a substrate such as a microscope observation glass plate using a flexible stamp.

  For soft stamping lithography, a flexible elastomeric stamp is used to make the molecules structurally adherence by “inking” and “stamping” and stamp on the substrate. Known from the prior art to replicate surface patterns. Such a method is described in, for example, Patent Document 1 / Patent Document 2, which is a document of the same applicant.

  The quality of molecular transfer by contact using this type of method is strongly influenced by the uniformity of the stamp pressure on the substrate during the stamping operation and the performance of the stamping operation to match the substrate surface. For deposition of microstructured or nanostructured molecular patterns, uniform pressure is desirable on both the macroscopic and microscopic scales, and the print quality is sensitive to surface irregularities, and the degree of irregularities Is within the range of the roughness parameter or waveform parameter of the surface, or more precisely, within the range of irregularities shown on the SL surface conforming to the ISO25178 standard. The high flexibility of the stamp is advantageous in terms of the ability to match the shape of the substrate surface, but it is possible to apply such a force to the stamp, in particular via mechanical means, to press it evenly against the surface. There is a disadvantage with regard to transmitting in contact with the stamp. For this purpose, the conventional solution employs a pressing device using gas pressure or vacuum. In such a pressing device, it is necessary to realize airtightness between the stamp and the pressing device. Due to the complexity of such devices, it is difficult to change stamps automatically, and as a result, complex deposition to be fully automated and productive by this technique.

  Accordingly, the present invention has the ability to automatically change the stamp, while applying a uniform and controlled pressure to press the stamp against the substrate during the stamping operation, thereby providing high quality transfer software. Aimed at a lithographic apparatus.

  In the field related to stamps used for stamping characters or drawings other than the field of the present invention, Patent Document 3 includes a structure surface called a printing surface on one side, and an elastomer layer having a surface facing the printing surface. A stamp is described which is coated and comprises a ferromagnetic wire in the layer. With these ferromagnetic wires, the stamp can be connected to a mounting portion called a grip mounting portion by a magnetic effect, and the stamp is stamped and printing is performed. Thus, a single gripping attachment can be used for the entire stamp set having this structure. This document is not limited to the stamp that realizes the deposition of the microstructure or the nanostructure, and the technique used for this stamp is not effective at all for solving the technical problem covered by the present invention. In fact, making the wire ferromagnetic makes it possible to couple the stamp to the gripping attachment and then mechanically apply pressure to the substrate, but this does not provide a uniform pressure at the desired scale.

  Patent Document 4 describes a method of impressing a mold or “stamper” for pressing an optical disc and magnetically maintaining the metal mold itself in an appropriate position during the engraving operation. is doing.

European Patent Publication No. 2036604 Specification US Patent Publication No. 2009/0807019 US Pat. No. 6,920,825 JP 2001-338445 A

In order to remedy the disadvantages of the prior art, the present invention provides an apparatus for soft lithography by transfer, comprising a flexible stamp capable of realizing the deposition of microstructures or nanostructures on a substrate, the flexible stamp comprising: ,
An elastomeric layer provided on one side with a structural surface capable of being deposited by transfer;
Proposing a device comprising an elastomer second layer in close contact with the surface of the first layer facing the structural surface, the second layer comprising an elastomer in which particles of soft ferromagnetic material are dispersed. .

  Due to the presence of soft ferromagnetic particles, an appropriate magnetic field can be applied and a uniform pressure can be applied to the stamp. The action of these particles is spread throughout the volume of the layer filled with ferromagnetic particles. This pressure is applied to the stamp without any contact, mechanical actuators or fluid. Therefore, the stamp can be kept flexible so that the shape of the substrate surface can be best taken. Flexible ferromagnetic particles do not continue to be magnetized when the magnetic field received by the particles stops working. By including soft ferromagnetic particles in the layer of flexible stamp, this ability to magnetize and demagnetize the layer allows the stamp to be easily handled with electromagnets without strict restrictions, and therefore extremely flexible Stamps can be easily modified, including stamps with and / or complex shapes.

  The invention may be implemented in a number of advantageous embodiments, as will be described below, each of which can be considered as a separate embodiment and an effective technical combination of the embodiments. It can be regarded as a part.

Advantageously, the size of the soft ferromagnetic particles is 10 μm to 200 μm. By making the particles finer, it becomes possible to pressurize the stamp uniformly on the substrate with a target scale. In this document, 1 μm corresponds to 10 ⁻⁶ meters.

  The proportion of particles in the second layer is advantageously between 50% and 95% by weight. By making the particles fine, such high levels can be reached without compromising the flexibility of the stamp.

  The elastomer that forms the two layers of the stamp is polydimethylsiloxane (PDMS). By using the same material, the soft ferromagnetic particles can have a high mass concentration while ensuring mechanical properties suitable for use as a stamp component. The stamp is made by two successive moldings, the molding comprising a first step of shaping and partially cross-linking the first layer with the deposited structured pattern without injecting particles, and then the first layer. And forming a second layer comprising premixed ferromagnetic particles. As a result of making the particles fine, the particles do not interfere with the polymerization of the stamp, and the particles remain suspended and uniformly distributed in the second layer during the polymerization.

  Advantageously, the device comprises magnetic operating means that can grip and apply a flexible stamp in order to be able to change the stamp automatically.

  The apparatus advantageously comprises a magnetic field generator disposed below the substrate and means for controlling the generator to initiate and adjust the pressing force of the stamp on the substrate. By disposing the magnetic field generator under the substrate, as described in Patent Document 1 or Patent Document 2, even when the macro stamp is provided with a layer containing soft ferromagnetic particles, An optimum pressing effect on the substrate surface can be obtained.

  The type of magnetic field generating device arranged under the substrate and its control mode are selected according to the properties, thickness, surface of the substrate, and the properties of the stamp used.

  According to one particular embodiment, the magnetic field generator is a magnet and the distance between the magnet and the stamp is controlled by the control means. The magnet may be a permanent magnet, an electromagnet, or a solenoid, and the electromagnet or solenoid is energized with a fixed voltage and an amperage current.

  According to another embodiment, the magnetic field generator comprises a solenoid, and the control means controls the amperage or voltage of the solenoid power supply.

  According to a particularly advantageous embodiment, the device comprises an electrode arranged between the magnetic field generator and the substrate and means capable of measuring the change in capacitance between the electrode and the second layer of the stamp. . With this feature, the pressing force of the stamp on the substrate can be measured in real time, and the magnetic field generator can be controlled accordingly. This ease of control is brought about by the presence of ferromagnetic particles in the stamp, which increases the conductivity of the stamp, so that this type of measurement is essentially a stamp made up of a non-conductive polymer. It is also possible to use.

  Thus, the device according to the invention can be fully automated and the magnetic gripping and deposition means are supported by a cross-slide carriage which can be moved according to three orthogonal axes. By adding the inking tank and the substrate mounting portion to the apparatus, the magnetic gripping means can be moved between the inking tank and the substrate mounting portion by the carriage of the cross slide.

  Advantageously, the apparatus can comprise a plurality of inking tanks containing different products to be deposited on the substrate. The ability to change stamps can have different stamps for depositing different products without intervening stamp cleaning operations, and can thus greatly increase the productivity of soft lithography operations.

In this connection, the invention also relates to an advantageously optimized soft lithography method carried out using the apparatus according to the invention, which method comprises:
-Taking the stamp with a magnetic gripping means;
-Moving the stamp onto the inking tank and bringing the structural surface of the stamp into contact with the contents of the tank;
-Removing the stamp from the tank;
-Transporting the stamp onto the substrate;
-Releasing the stamp from the magnetic gripping means;
-Actuating a magnetic field generating device located under the substrate to uniformly stamp the stamp on the substrate.

  The present invention will now be described in further detail in connection with the preferred non-limiting embodiment shown in FIGS.

It is sectional drawing of the stamp for soft lithography seen from the front. It is sectional drawing of the macro stamp for soft lithography seen from the front. FIG. 5 is a front cross-sectional view of a stamp and substrate assembly and elements that enable stamping on the substrate for transport and printing of the stamp. 1 is a top perspective view of an automatic soft lithography apparatus. The details of the above-mentioned device comprising a macro stamp and its gripping means are shown in a right perspective view. It is front sectional drawing which shows one step which stamps a stamp to a board | substrate. It is front sectional drawing of the other step which stamps a stamp to a board | substrate. It is front sectional drawing of another step which stamps a stamp to a board | substrate, and is a step where the pressing force to this stamp is too high. It is a graph which shows the change in the capacity | capacitance of the capacitor | condenser pinched | interposed between the 2nd layer of a stamp and the electrode arrange | positioned under a board | substrate.

FIG. 1: According to an embodiment of a soft lithography stamp 1, the stamp 1 is made of polydimethylsiloxane (PDMS) and comprises a first layer 3 according to its thickness, the first layer 3 being printed It comprises a microstructured or nanostructured surface called surface 31 that can be deposited by transfer onto a substrate, and a second surface 32 that is substantially parallel and opposite the first. The second layer 2 that is in close contact with the first layer 3 along the second surface 32 is also made of PDMS, and the ferrite particles, that is, iron (III) oxide (Fe ₂ O ₃ ), manganese, and zinc are mainly used for the PDMS. Filled with soft ferromagnetic particles such as ceramic as a component. Alternatively, pure iron particles that may prevent oxidation, particles made of an iron-nickel-molybdenum alloy or iron-silicon, such as SuperMalloy®, and generally any soft ferromagnetic material, ie magnetic field A soft ferromagnetic material that is magnetized under action and no longer has a remanence when it is no longer subjected to the magnetic field can be used. Soft ferromagnetic materials exhibit low magnetic permeability. Therefore, soft ferromagnetic materials
The possibility of generating a reaction to the magnetic field and in particular the magnetic attraction from the stamp to the substrate,
-Low magnetic permeability sufficient to use the same magnetic adsorption device for various stamps with equally uniform pressure performance,
-Enabling rapid response to magnetic stimulation and cessation of the stimulation, resulting in high ink transfer rates;
-Make sure there is no residual magnetism after use so that the stamp does not adsorb contaminants such as metal dust during storage,
Provide a good compromise between

  These particles are substantially spherical with a diameter of 10 μm to 200 μm.

  FIG. 2: According to the embodiment of the macro stamp 10, the macro stamp includes a plurality of stamps 13 and a surface 132 that faces the printing surface 131 in close contact with the macro stamp body 12. Preferably, the stamp 13 is made of PDMS. The main body 12 is made of PDMS filled with 50 to 95% by weight of soft ferromagnetic particles. The magnetic permeability of soft ferromagnetic particles and the elimination of residual magnetism in the layer comprising these ferromagnetic particles enables the coupling of stamps in a macro stamp without the problem of magnetic interaction between different stamps. Become.

  The principle of manufacturing stamps or macro stamps according to these embodiments is substantially the same. A first step of shaping the layers 3, 13 with a micro or nanostructure pattern and without ferromagnetic particles is carried out. Following this molding step, for example, the layer is precured for 15 minutes at 60 ° C. and partially crosslinked. Thereafter, the layers 2 and 12 containing the ferromagnetic particles are coated on the first layer. These two layers are then co-cured. The ability to adhere one layer to another during a subsequent co-curing step while the first partial cross-linking prevents the two layers from mixing during the coating of a layer filled with ferromagnetic particles To maintain.

  The presence of ferromagnetic particles makes the layers 2, 12 containing the particles sensitive to magnetic fields and this property can be used for stamping operations.

  Also, the presence of these particles changes the conductivity of the layer and reduces the electrical resistance to tens of thousands of ohms.

  The soft lithography method is automated using the change in these characteristics.

FIG. 3: According to an embodiment, the presence of the ferromagnetic layers 2, 12 makes it possible to grip the stamp 1 or the macro stamp 10 with a device comprising a coil or solenoid 20 that can generate a magnetic field. When the coil is energized with a current, a magnetic field is generated, and the stamp 1 or the macro stamp 10 can be adsorbed by the magnetic field, and can be moved when the stamp is attached to the coil 20. In order to stamp the stamp 1 onto the substrate 30, for example, a glass slide, the power to the coil is cut off. A device 40 for generating a magnetic field disposed under the substrate 30 tends to adsorb the stamp or macro stamp and press it against the substrate, thereby forcibly aligning the stamp with the substrate surface. The force for impressing the stamp 1 onto the substrate 30 can be controlled in different modes depending on the nature of the magnetic field generator 40. Non-limiting examples include
-The magnetic field generator 40 can be provided with a permanent magnet, so that the adjustment of the pressing force is realized by the distance between the stamp 1 and the magnet, either by moving the magnet or by moving the stamp.
-The device 40 can also be embodied as a coil or solenoid, so that the pressing force is adjusted by changing the strength or voltage of the coil power supply.
-The device 40 can also be implemented with an electromagnet, i.e. a solenoid surrounding the magnet, so that the pressing force is adjusted by adjusting the current intensity of the power supply of the solenoid and / or the distance between the stamp and the electromagnet.

  The adjustment of the force can be controlled in the effective contact area between the stamp 1 and the substrate. In order to predict this contact area, the electrode 50 is advantageously arranged between the magnetic field generator 40 and the substrate 30. By utilizing the conductivity of the layers 2 and 12 filled with ferromagnetic particles, the variation in capacitance representing the amount of air that is an insulating portion existing between the stamp 1 and the substrate 30 can be measured. , Proportional to the effective contact area between the stamp and the substrate. An advantage of this measurement is that the magnetic field has no effect.

  FIG. 6: The electrode 50 disposed between the magnetic field generator and the substrate 30 forms a capacitor with the second layers 2 and 12 of stamps filled with ferromagnetic particles and the dielectric space separating the two. . By measuring the variation in the capacitance of the capacitor or the variation in the capacitance of the electric circuit including the capacitor, which is affected by the thickness of the space, the signal characteristics of the pressing force of the stamps 1 and 10 on the substrate 30 can be obtained. can get.

  FIG. 6A: Therefore, when the stamp 1 is not in contact with the substrate, the capacitance of the capacitor formed by the electrode 50 and the second layer 2 disposed under the substrate is low. FIG. 6B: As the distance between the two electrodes decreases, the capacitance increases and reaches a plateau.

  FIG. 7 shows a change 600 in the capacitance 500 of the capacitor due to the pressing force 400 of the stamp on the substrate. When the electrostatic capacity reaches the first plateau 610, the electrostatic capacity experimentally corresponds to the optimum pressing force of the stamp 1 or the macro stamp 10 on the substrate 30.

  FIG. 6C: When the pressing force becomes excessive, the stamp is in a crushed state, the capacitance of the capacitor is significantly increased, and the plateau is increased to a plateau corresponding to the state in which the stamp 1 is completely crushed on the substrate.

  FIG. 7: The second plateau 620 in the change in capacitance corresponds to the crushing state of the stamp.

  Accordingly, by tracking the capacitance change of the capacitor formed by the electrode 50 and the second layer, the magnetic field is obtained so as to obtain the optimum pressing force corresponding to the first plateau 610 measured by this capacitance change. The generator can be controlled.

  FIG. 4: According to an embodiment of the automatic soft lithography apparatus 100, the apparatus comprises a table 120 on which guides 125, 126 supporting the gantry 200 are fixed. The gantry can be translated relative to the table 120 along the longitudinal axis as can be seen from the guides 125, 126 by the powering means 300. The gantry supports a magnetic gripping device 220 for the stamp or macrostamp 10 so that it can move longitudinally with respect to the table 120 along with the gantry 200. Along the longitudinal axis of the table, the table supports five stations corresponding to the various operations required for deposition by stamping.

  The first station 110 corresponds to a stamp or macro stamp storage area. The magnetic gripping device 220 can use different stamps and can automatically change these stamps.

  The second station 140 is, for example, a deposition area that can receive a substrate such as a slide. This station advantageously comprises an electromagnet located under the slide to ensure that the stamp or macrostamp can be uniformly pressed against the substrate surface during stamping.

  The third station 160 is an area where the stamp or the macro stamp is dried by blowing air.

  The fourth station 150 is a station known as an “inking station”. The station includes a plurality of tanks that contain solutions or molecules to be deposited on the substrate. One of the tanks may contain a solution for cleaning the stamp or macro stamp.

  The fifth stations 141, 142, 143, 144 comprise other substrates for receiving structured deposition. In this embodiment, this station can accommodate up to four slides. According to another embodiment, the magnetic field generator associated with this station comprises a permanent magnet.

  FIG. 5: Gantry 200 includes a cross member 203 that rests on guides 125, 126. The gantry supports the guide element 204 and the motorizing element 205, by which the carriage 202, called a cross slide, is known as a transverse line parallel to the cross member 203, ie perpendicular to the longitudinal direction of the table 120. Make it movable in the direction.

  The cross slide 202 allows movement of a guide element 207 extending in one direction, known as the vertical direction, orthogonal to the longitudinal and transverse directions, and a carriage 201, known as the vertical direction, that supports the magnetic gripping device 220. A motorizing element 206 is supported.

  When the magnetic gripping device is composed of three solenoids 221 and the solenoids are energized with current, the macro stamp 10 or the stamp can be carried to the next station.

  Alternatively, the gripping device may be composed of three electromagnets that generate a magnetic field capable of carrying a stamp without being energized with an electric current. In this embodiment, the stamp can be released by supplying power to the solenoid of the electromagnet. This embodiment is advantageously used for extremely flexible and lightweight stamps. For heavier stamps or macro stamps, the suction force can be increased by reversely feeding the solenoid.

  Thus, after taking the stamp 1 or macro stamp 10, the apparatus first transports the stamp or macro stamp to an inking station 150 that is immersed in one of the tanks. Inking is performed by immersing the stamp in one of the tanks. Advantageously, the magnetic gripping device modulates the power supply of the solenoid during immersion so that the stamp can be swung in the solution bath to enhance inking uniformity.

  The stamp attached to the magnetic gripping means 220 is then conveyed onto the drying area 130. After that, a stamp is stamped on one of the slides. Alternatively, the stamp can be changed for each stamping operation.

  The above description clearly shows that the object of the present invention is achieved through various features and effects of the present invention. In particular, according to the present invention, the application pressure of the soft lithography stamp or macro stamp to the substrate surface can be easily and efficiently controlled, and the automation of the soft lithography method is facilitated by incorporating an automatic stamp change. The present invention is particularly suitable for the production of biochips.

1 (Soft Lithography) Stamp 2 Elastomer Second Layer 3 Elastomer First Layer 10 (Macro) Stamp 12 Macro Stamp Body / Elastomer Layer 13 Elastomer First Layer / Stamp 20 Coil or Solenoid (Magnetic Means)
30 Substrate 31, 131 Structure surface (printing surface)
32 Micro or nanostructure surface (second surface)
40 magnetic field generator 50 electrode 100 (automatic) soft lithography apparatus 110 first station (storage area)
120 Table 125, 126 Guide 130 Drying area 132 Surface 140 Second station (board mounting part)
141, 142, 143, 144 5th station (board mounting part)
150 4th Station (Inking Tank)
160 Third station 200 Gantry 201, 202 (cross slide) carriage 203 Cross member (carriage)
204, 207 Guide elements 205, 206 Motorizing element 220 Magnetic gripping device (magnetic gripping means)
221 Solenoid (magnetic means)
300 Motorizing means 400 Pressing force 500 Capacitance 600 Change 610 First plateau 620 Second plateau

Claims (11)

An apparatus for soft lithography (100) for transferring a microstructured or nanostructured deposit to a substrate (30), said apparatus comprising:
An elastomeric layer (3, 13) provided on one side with a structural surface (31, 131) capable of realizing said deposition by transfer;
-An elastomer second layer (2, 12), in close contact with the surface (32, 132) facing the structural surface (31, 131) of the first layer (3, 13), A device comprising a flexible stamp (1, 10) comprising said second layer (2, 12) made of elastomer in which particles of magnetic material are dispersed.   Device according to claim 1, characterized in that the size of the soft ferromagnetic particles dispersed in the second layer (2, 12) is between 10m and 200m.   The device according to claim 2, characterized in that the proportion of soft ferromagnetic particles in the second layer (2, 12) of the stamp (1, 10) is between 50% and 95% by weight.   The apparatus according to claim 1, wherein the elastomer forming the two layers of the stamp is polydimethylsiloxane (PDMS).   2. Device according to claim 1, characterized in that it comprises magnetic means (20, 221) capable of gripping and applying the flexible stamp (1, 10).   A magnetic field generator (40) disposed under the substrate (30); and means for controlling the generator to initiate and adjust the pressing force of the stamp on the substrate. The apparatus of claim 1.   An electrode (50) disposed between the magnetic field generator (40) and the substrate (30), and the electrode (50) and the second layer (2, 12) of the stamp (1, 10). The apparatus according to claim 6, further comprising means capable of measuring a change in capacitance between the two.   The apparatus according to claim 6, wherein the magnetic field generation device is a magnet, and the distance between the magnet and the stamp is controlled by the control means.   The apparatus according to claim 6, wherein the magnetic field generation device includes a solenoid, and the control unit controls a current or a voltage of a power source of the solenoid.   The magnetic gripping and attaching means are supported by a cross slide carriage (201, 202, 203) that can move the means according to three orthogonal axes, and an inking tank (150) and a substrate mounting part (140, 141, 142, 143, 144), the magnetic gripping means (220) can be moved between the inking tank and the substrate mounting portion by the carriage of the cross slide. Apparatus according to claims 5 and 6. A soft lithography method performed using the apparatus of claim 10, wherein the method comprises:
Taking the stamp (1, 10) with magnetic gripping means (220);
-Moving the stamp onto the inking tank (150) to bring the micro- or nanostructured surface (32, 132) of the stamp into contact with the contents of the tank;
-Removing the stamp from the tank;
Conveying the stamp onto the substrate (30);
-Releasing the stamp from the magnetic gripping means;
Activating a magnetic field generator (40) disposed under the substrate (30) to uniformly stamp the stamp (1, 10) onto the substrate (30). .

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